The present invention relates generally to windshield wiper systems, and more particularly, to windshield wipers systems used on high-curvature windshields.
A windshield wiper system is responsible for clearing rain, snow, and other debris from a vehicle windshield, typically by movement of a rubber blade element across the windshield surface. Windshield wiper arms used in the automotive and aerospace industries generally apply a fixed blade load, which is set at the factory or during the installation of the wiper system on the vehicle. The method for applying this blade load can vary. For example, tension spring mechanisms, compression spring mechanisms, flexural cantilever loading, or conical spring washer assemblies are all methods for applying blade load. Although small blade load variation is inevitably caused by the wiper arm rotation that lengthens or shortens the load member as it traverses the wiper cycle, each method is fundamentally similar in that they are not designed to customize blade load as a function of wiper angle. As currently implemented, the connection point nearest to the hub is typically internal to the arm body itself, and there is no secondary attachment point on the drive mechanism. While this design is favorable from an installation and maintenance perspective, its independent nature of design essentially guarantees that the blade load cannot be a function of the angular sweep position.
During operation of a conventional windshield wiper on windshields with high curvature, the wiper arm rotates away from the drive mechanism as it traverses the high-curvature region. The wiper's rotation causes increased blade load and component stress within the wiper system. The additional blade load also increases the friction on the blade as it crosses the high-curvature region of the windshield. The result of increased blade load could be system lock-up, increased rating requirements of drive components, or reduced system reliability. Therefore, a need exists to customize the blade load of a wiper assembly to improve the operation of wiper systems.